diff --git a/actions/inbox/Create.php b/actions/inbox/Create.php
index 8af2755..d3a5310 100755
--- a/actions/inbox/Create.php
+++ b/actions/inbox/Create.php
@@ -84,7 +84,7 @@ if (isset($data->object->cc) && is_array($data->object->cc)) {
         try {
             $to_profiles = array_merge($to_profiles, $discovery->lookup($cc_url));
         } catch (Exception $e) {
-            // Invalid actor found, just let it go.
+            // Invalid actor found, just let it go. // TODO: Fallback to OStatus
         }
     }
 } elseif (empty($data->object->cc) || in_array($data->object->cc, $public_to)) {
@@ -93,7 +93,7 @@ if (isset($data->object->cc) && is_array($data->object->cc)) {
     try {
         $to_profiles = array_merge($to_profiles, $discovery->lookup($data->object->cc));
     } catch (Exception $e) {
-        // Invalid actor found, just let it go.
+        // Invalid actor found, just let it go. // TODO: Fallback to OStatus
     }
 }
 
diff --git a/classes/Activitypub_attachment.php b/classes/Activitypub_attachment.php
index 0357d1b..f053f0e 100755
--- a/classes/Activitypub_attachment.php
+++ b/classes/Activitypub_attachment.php
@@ -50,26 +50,19 @@ class Activitypub_attachment extends Managed_DataObject
     public static function attachment_to_array($attachment)
     {
         $res = [
-                        '@context'  => [
-                                "https://www.w3.org/ns/activitystreams",
-                                [
-                                        "@language" => "en"
-                                ]
-                        ],
-                        'id'       => $attachment->getID(),
-                        'mimetype' => $attachment->mimetype,
-                        'url'      => $attachment->getUrl(),
-                        'size'     => intval($attachment->size), // $attachment->getSize ()
-                        'title'    => $attachment->getTitle(),
-                        'meta'     => null
-                ];
+                'type'      => 'Document',
+                'mediaType' => $attachment->mimetype,
+                'url'       => $attachment->getUrl(),
+                'size'      => intval($attachment->size), // $attachment->getSize ()
+                'name'      => $attachment->getTitle(),
+        ];
 
         // Image
-        if (substr($res["mimetype"], 0, 5) == "image") {
+        if (substr($res["mediaType"], 0, 5) == "image") {
             $res["meta"]= [
-                                'width'  => $attachment->width,
-                                'height' => $attachment->height
-                        ];
+                    'width'  => $attachment->width,
+                    'height' => $attachment->height
+            ];
         }
 
         return $res;
diff --git a/classes/Activitypub_profile.php b/classes/Activitypub_profile.php
index b3f8d37..b628562 100755
--- a/classes/Activitypub_profile.php
+++ b/classes/Activitypub_profile.php
@@ -120,8 +120,10 @@ class Activitypub_profile extends Managed_DataObject
             'attachment' => [],
             'icon' => [
                 'type'      => 'Image',
-                'mediaType' => 'image/jpeg',
-                'url'       => $profile->avatarUrl()
+                'mediaType' => 'image/png',
+                'height'    => AVATAR_PROFILE_SIZE,
+                'width'     => AVATAR_PROFILE_SIZE,
+                'url'       => $profile->avatarUrl(AVATAR_PROFILE_SIZE)
             ]
         ];
 
diff --git a/utils/explorer.php b/utils/explorer.php
index f010878..829a2c6 100755
--- a/utils/explorer.php
+++ b/utils/explorer.php
@@ -241,9 +241,70 @@ class Activitypub_explorer
         $apRSA->public_key = $res['publicKey']['publicKeyPem'];
         $apRSA->store_keys();
 
+        // Avatar
+        if (isset($res['icon']['url'])) {
+            $this->_store_avatar($profile, $res['icon']['url']);
+        }
+
         return $profile;
     }
 
+    /**
+     * Download and update given avatar image
+     *
+     * @author GNU Social
+     * @param string $url
+     * @return Avatar    The Avatar we have on disk. (seldom used)
+     * @throws Exception in various failure cases
+     */
+    private function _store_avatar($profile, $url)
+    {
+        if (!common_valid_http_url($url)) {
+            // TRANS: Server exception. %s is a URL.
+            throw new ServerException(sprintf('Invalid avatar URL %s.'), $url);
+        }
+
+        // @todo FIXME: This should be better encapsulated
+        // ripped from oauthstore.php (for old OMB client)
+        $temp_filename = tempnam(sys_get_temp_dir(), 'listener_avatar');
+        try {
+            $imgData = HTTPClient::quickGet($url);
+            // Make sure it's at least an image file. ImageFile can do the rest.
+            if (false === getimagesizefromstring($imgData)) {
+                throw new UnsupportedMediaException('Downloaded group avatar was not an image.');
+            }
+            file_put_contents($temp_filename, $imgData);
+            unset($imgData);    // No need to carry this in memory.
+
+            $id = $profile->getID();
+
+            $imagefile = new ImageFile(null, $temp_filename);
+            $filename = Avatar::filename($id,
+                                         image_type_to_extension($imagefile->type),
+                                         null,
+                                         common_timestamp());
+            rename($temp_filename, Avatar::path($filename));
+        } catch (Exception $e) {
+            unlink($temp_filename);
+            throw $e;
+        }
+        // @todo FIXME: Hardcoded chmod is lame, but seems to be necessary to
+        // keep from accidentally saving images from command-line (queues)
+        // that can't be read from web server, which causes hard-to-notice
+        // problems later on:
+        //
+        // http://status.net/open-source/issues/2663
+        chmod(Avatar::path($filename), 0644);
+
+        $profile->setOriginal($filename);
+
+        $orig = clone($profile);
+        $profile->avatar = $url;
+        $profile->update($orig);
+
+        return Avatar::getUploaded($profile);
+    }
+
     /**
      * Validates a remote response in order to determine whether this
      * response is a valid profile or not